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File Formats

Image File Formats describe how images such as pictures and logos are saved and preserved.  Having a greater understanding of Image File Formats will help you and your designer to select the most appropriate format to achieve the best result when you are printing an image, logo, picture or graphic.

File formats are divided into two principle types, pixel based and vector based.

PixelsPixels

These are a collection of dots closely connected to form an image when illuminated on a computer screen or printed onto paper or board. Pixel based files can be black and white; grayscale or halftone i.e. continuous tone, usually of a picture; or coloured. The dot structure of pixel based images is significant when judging the final printed result. The resolution measured in dots per square inch or dots per cm2 dictates the visibility of the pixels.  With a high resolution image, the pixels are less visible; pictures look sharper with the optimum resolution being 300d.p.i.

In contrast the pixels in low resolution images when enlarged become more visible as a result curves and edges appear to get rough or jagged. Images taken from web pages on the internet, which usually have a resolution of 72 dpi, should be avoided for this reason when commercially printing.

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All scanned images are pixel based as are digital camera images and those created with ‘paint’ applications. e.g. Microsoft Paint® The most common file format for using pixel based images is Adobe Photoshop®.

 

Vector Based Format Images

The vector based image format is one based on the mathematical formulation of vectors. Graphical representation, using defined shapes or lines to construct the outline of objects are vector based.  The principle advantage of using vector based images is that enlargement does not cause the image to deteriorate.  Adobe Illustrator® and Benugorest LogoMacintosh Freehand® are two of the most popular applications for producing vector based images. Most logos are created in vector based programmes.

Vector Based Image

 


Is there a preferred format?

The two formats that maintain the necessary information for commercial printing are TIFF (Tagged Image File Format) and EPS (Encapsulated PostScript). Deciding on which of these two formats to use is more a question of what other applications can do to the file after it is imported into a software package.  Choose TIFF for pictures or EPS for vectors. Both formats work well on the Macintosh and PC computers.

Here are suggestions on which format to save your image in to maximize your design project.

EPS File Format Options (Encapsulated Postscript Format)

The Encapsulated Post Script file format is generally the preferred format for importing vector based images. It’s the universal way of saving files from FreeHand and Illustrator and is often the best method for saving from PhotoShop.

TIFF File Format Option (Tagged Image File Format)

The Tag Image File Format was developed to offer a convenient means of saving graphics that are scanned or generated electronically. It offers, if it represents the source file, the highest resolution pixel based image.

Other formats to be aware of are:

Persil LogoJPEG (Joint Photographic Experts Group) are pixel based images, used to display photo and other continuous tones. Such files support CMYK (cyan, magenta, yellow and black) and grayscale colour information. JPEGs are compressed files. Large images, measured in megabytes, are made smaller when saved as jpegs. This reduction is achieved by disgarding some of the images data. Depending on how large the file was to begin with such compression can result in the picture being unsuitable to print from. However, if the JPEG has been saved as a high quality one it is suitable for use in the print process.

GIF File Format Options (Graphic Interchange Format)Blues

GIF is file format that is not suitable for print. GIFs are used for compressing images like computer graphics and are far more suited for web design or to exchange images through e-mail and user groups.

 

If all of this sounds too much like jargon or technical speak and you need further help with your project or design, please do not hesitate to contact us. We will be happy to help you.